The four men convicted of murdering a Novato man in his driveway have until Jan. 16 to file motions for a new trial, a judge said Wednesday.

The order by Judge Terrence Boren moves the case — which has been stalled over allegations of drug crimes by a former Novato detective — toward a possible conclusion in March. Boren said he would rule on the motions on Feb. 25, and if he rejects them, the sentencing will follow in about a week.

The drug allegations involve Jehan "J.J." Amdjadi, a former Novato detective who was also a member of the county's multiagency drug squad, the Marin County Major Crimes Task Force. Amdjadi was the initial lead detective assigned to investigate the murder of Novato resident Tong Van Le in 2008.

Four suspects were convicted of Le's murder after years of litigation and a complex, six-month trial. But just before the sentencing in September, authorities disclosed that an internal investigation had implicated Amdjadi in alleged drug crimes, including cocaine use and stealing drug evidence meant for destruction.

Defense attorneys say the allegations taint Amdjadi and the convictions. Moreover, they say District Attorney Ed Berberian shirked his obligation to disclose information that would impeach the credibility of a key prosecution witness like Amdjadi.

In court papers filed Wednesday, Berberian acknowledged that his office first learned of the Amdjadi allegations in early April — while the trial was still in progress — but he did not disclose them at the time because they were "at best speculation and rumors at levels of hearsay that were two or three levels deep."

Instead, Berberian said, he promptly notified Novato police and the task force so internal investigations could commence. The investigations were completed in July, and eventually records on Amdjadi were released to defense attorneys. By then, the defendants already had been convicted.

Defense attorneys Mary Stearns and Tara Higgins, joined by defense attorney Carl Gonser and public defender Brian Morris, continued to press for more records Wednesday, telling the judge that Berberian's office was trying to hobble their investigation with incomplete information and redacted documents.

In particular, defense attorneys are trying to learn the name of a task force source known as "Confidential Informant No. 1," apparently the initial whistleblower against Amdjadi. They also seek the locations of facilities where the secretive task force stores its drug evidence.

Berberian said he would not reveal the identity of Confidential Informant No. 1 without a court order, and denied withholding information he was obliged to disclose. He also said there is nothing about Amdjadi's alleged conduct that would point to anyone else as the killers of Tong Van Le.

"We've given them what we have," he said.

Amdjadi's lawyer, Alison Berry Wilkinson, has declined to comment on the matter.

Berberian said his office has not decided whether Amdjadi will face criminal charges.

Le, 44, was gunned down at his Hamilton home in 2008 to prevent his testimony about a robbery at his liquor store in San Francisco, authorities said. One of the accused killers, Sean Washington, eventually admitted his involvement and testified against the other suspects in exchange for a manslaughter conviction.

In May, a Marin County jury convicted the other alleged conspirators — Larry Blay Jr.; his brother, Deandre; Kevin Abram; and C. Autis Johnson — of murder and related charges. Johnson's mother, Anchulita Uribe, was convicted of being an accessory after the fact and was sentenced in July.